Microstructure development on sintered Ti/HA biocomposites produced by powder metallurgy

Titanium-based composites with in-situ calcium and phosphor phases were prepared by powder metallurgy processing with titanium and hydroxyapatite (HA) powders. The mixtures were performed in a friction mill with alcohol for 5 hours, dried in a rotating evaporator, pressed at 600 MPa and sintered at 1200 ºC for 2 hours in argon atmosphere. Crystal phases of the as-fabricated composite are found to be, α-Ti, CaTiO3, Ca3(PO4)2 and Ti xPy phase(s). The analyses revealed that titanium particles were covered with a compact layer of Ti xPy and CaTiO3 phases, which resulted from the decomposition of HA into CaTiO3 and β-Ca3(PO4)2 at approximately 1025 ºC. Then the reactions were followed by the decomposition of β-Ca3(PO4)2, resulting in the growth of CaTiO3 layer and in the nucleation and growth of Ti xPy phase(s).